The invention pertains to a blind-stitch sewing machine including a fabric bending arrangement which makes the fabric to be sewn bulge as it advances.
Blind-stitching machines are known as represented in German Patent No. 11 02 535. In this patent, the fabric bender is axially displaceable in a bearing sleeve against the opposing force of a helical compression spring mounted in this sleeve. The bias of the spring can be changed without thereby affecting the position of the fabric bender relative to the sleeve. The sleeve extends perpendicular to a throat plate mounted on the head of the blind-stitching machine and is axially displaceable to-and-fro on a fabric support arm of the machine by means of a drive shaft supported in said arm. The sleeve is connected to the drive shaft such that the minimum distance by which the sleeve may approach the throat plate when the machine is in operation can be changed. A stop, against which the fabric bender curves or bulges the material to be sewn, is pivotably supported by the throat plate on the side away from the fabric bender so as to pivot about an axis transverse to the direction of advance of the material being sewn or stitched. The stop can be adjusted by a setting screw engaging to stop and threaded into the throat plate in order to assure that the depth of stitching into the material being stitched by the arc needle pivoting to-and-fro on the side of the throat plate away from the fabric bender, which stitch depth is defined by means of the particular setting of the minimum distance between the driven sleeve and the throat plate, is maintained even when said material becomes transiently thicker. For the same purpose also, the bias of the helical compression spring loading the fabric bender can be set correspondingly.
Known blind-stitch sewing machines are not immediately suitable for the sewing of labels having an unevenly thick rim onto the inside of finished garments. There is no assurance that when sewing such a label along its rim, the arc-needle of the blind-stitching machine will always penetrate equally deep into the garment, such as, for example, when sewing a tetragonal label having two parallel edges folded over so that the label includes both single-ply label edges and the double-ply ones. This is, however, required to affix a label in a problem-free manner. If, for instance, the label is to be sewed onto a garment having a thin lining, the arc-needle may not penetrate the fabric layer covered by the thin lining, and on the other hand the arc-needle may not avoid stitching the lining.
Using straight needles, it is known to sew labels, cut from a band and of which both cut edges were folded, to the inside of finished garments, at all four label edges. In such arrangements, the needle perpendicularly and totally pierces both the label edges and the garment. As a drawback, the stitchings at the label edges are visible both on the label and also on the garment outside. Examples of such arrangements are represented by U.S. Pat. No. 2,560,186 and German Auslegeschrift 1,660,818. Moreover it is known, as disclosed in German Patent Nos. 3,515,189 and 3,519,849, to stitch labels spot-wise to garments by means of special blind-stitch sewing machines producing so-called point locks. These stitches are not visible on the garment outside.